Choosing a fish species
There are many different species of fish that can be used in an aquaponic system, depending on your local climates and available supplies. Our local climate in Arizona, Western USA, allows us to grow Tilapia year around.. There are also a few choices for year round fish that we could grow, but they often take a longer time to mature. If you live in a cooler climate you might be looking at growing Trout all year round, or perhaps another locally produced fish species.
In deciding what is the best species for you to grow, you should take a few factors into account, most importantly is what you want from your system. If you don’t want to eat your fish then you probably won’t want to grow edible fish, or you may want to grow an edible fish that can live year-round in your area, so that you’re not having to harvest fish out seasonally. The second most important factor is ‘What’s available?’ You need to be able to buy fish to stock your system, even with species such as Tilapia that breed readily; you need to get your broodstock in the first place.
Numbers of Fish
This can be quite a hot topic of debate amongst people who practice aquaponics. Stocking levels of fish within a system can be as high as many intensive recirculating aquaculture systems, however the higher the stocking density the higher the likelihood of things going wrong. In very heavy stocking densities, you need to keep a constant eye on all water parameters to be sure that conditions are kept at optimum levels.
Importance of fish
Fish are the power house of an aquaponics system. They provide the nutrients for the plants; and if your growing edible fish, then they also provide protein for yourself. Keeping fish may be a little daunting to some, especially those without any prior experience, however you shouldn’t be discouraged. Keeping fish in an aquaponic system is more simple than keeping aquarium fish. As long as you follow simple guidelines then growing fish from fingerling size to ready to eat fish can be extremely simple.
Types of fish we grow:
Originally found in Africa, Tilapia has been farmed for more than 2,500 years. Tilapia is a perfect fish for aquaponics because of its rapid growth, large size, and because it tastes great. This hardy fish can adapt to most any condition with the exception of water temperature. Tilapia prefer warm water – at least 75 degrees Fahrenheit. It takes about 9 months for Tilapia to grow to a harvestable size, about 1.5 pounds.
What does Tilapia eat? At MyOwnAquaponics, we feed our fish duckweed, ground-up salad greens from the greenhouse, commercial feed, and worms. In addition, tilapia love to eat algae from the side of the tank.
Here’s a list of useful aquaponic species with a few details about each
Barramundi, also known as Asian sea bass, are often grown in aquaponic systems through the warmer months of the year. Most growers will buy fairly mature stock so that they can harvest larger fish at the end of the growing season. Barramundi that is grown in an aquaponic system has an exceptionally clean, crisp taste. Growing your own Barramundi excites guests and is the envy of neighbors. They provide a decent harvest at the end of the season and are one of the more majestic species of edible fish.
There are many different species of catfish around the world that are well suited to aquaponics. Catfish are the most widely farmed aquaculture species in the United States that on June 25, 1987, President Ronald Reagan established National Catfish Day to recognize the value of farm-raised catfish. Catfish is high in Vitamin D and farm-raised catfish contains low levels of omega-3 fatty acids and a higher proportion of omega-6 fatty acids. Catfish don’t have scales so they need to be skinned. Plus they are quick growers and have a good food conversion ratio.
There are many species of carp that could be very well suited to aquaponics. Unfortunately because of their reproductive capabilities, their tough nature and ability to readily adapt in many areas of the world; carp have become noxious pests to native waterways and the environment. So much that they are not easily obtainable and often there are high fines and fees for keeping them. In most western cultures, carp also have a fairly poor reputation as an edible fish; however, carp is still the most widely cultured fish in the world as it’s grown throughout most of Asia.
Although some people may group these with the carp, goldfish will be treated separately highlighting the differences between the two as they will be sold as, at local pet shops or fish suppliers. Goldfish are generally pretty tough and make a great addition to an aquaponic system. In many areas, they will breed in a tank, although they generally need plant cover within the tank to breed.
This native Australian fish is worth a special mention here as it has the highest levels of omega three oils of any fish species in the world. In fact, it’s so high in omega three oils that growers are trying to breed the oil out of them. In other word, they are trying to breed a less oily fish because they’ve found people don’t like the high oil content.They require warm water and consume an omnivorous diet. Very well suited to an aquaponic system, they grow quickly and fingerlings are readily available in warmer areas.
Koi, another species of carp, but better known as “Koi” rather than carp. Koi are very common within many Asian communities and they are often found in large ornamental ponds. For those who love Koi, an aquaponic system is a great proposition for stocking the fish. These fish are among the longest-living vertebrates with some living over 200 years. Developed in China more than a thousand years ago via selective breeding, the koi is a cold-water fish that will eat a wide variety of foods including peas, lettuce, and watermelon. Koi will recognize the person feeding them and gather around that person during feeding times. They can be trained to take food from one’s hand.
The second most cultured fish in the world and extremely popular in Aquaponics’ systems. They are an ideal species for aquaponics for many reasons. They are easy to breed, fast growing, withstand very poor water conditions, consume an omnivorous diet and are good eating. The only downfall for some people will be that Tilapia require warm water. If you live in a cool area, you are far better off growing a fish species that will grow well in your temperature range rather than trying to heat the water. Tilapia are also a declared pest in many areas. Tilapias have very low levels of mercury, low in saturated fat, low calorie, low carbohydrate, and low sodium protein source. It is a very good source of phosphorus, niacin, selenium, vitamin B12, and potassium.
Trout are a great fish for aquaponic systems where water temperatures are a little cooler. Trout prefer water temperatures between 10°C and 20°C. They have extremely fast growth rates and excellent food conversion ratios. They can sustain on salmon eggs, worms, minnows, cut bait, corn, or marshmallows. Though somewhat bony, the trout is considered to be tasty; however, the flavor of the fish is highly influenced by the fish’s diet. In addition, trout contain one of the lowest amounts of dioxins of all oily fishes.
There are other fish species which are quite suitable for aquaponics that might be available in your local area within the United States such species as Bluegill are often available.
Other aquatic animals that can be incorporated into an aquaponic system are fresh water mussles, fresh water prawns, and fresh water crayfish. Mussles are a filter-feeder and do a great job of helping to clean the water. Mussles will happily grow in flooded grow beds or can be incorporated into fish tanks. Crustaceans make a nice addition to an aquaponic’s system and there are a few different species available depending on your location and water temperatures.
Types of veggies we grow:
We are often asked which plants grow well in an aquaponic’s system and it seems that most herbs and vegetables adapt well to aquaponics. Of course some plants won’t do as well when using different methods. Media filled beds seem to be the most successful for growing a large range of plants and you can grow just about anything.
Most herb varieties (such as basil, chives and cilantro) can be grown using the same plant spacing. Other crops (such as tomatoes, egg plant, melons, beans, cucumbers, etc.) can be grown using the appropriate plant spacing. Estimated numbers of heads of lettuce is based on yearly production in a controlled environment. Estimated pounds of fish is based on fish type and amount of breeding space.
Aquaponic’s systems will grow just about anything. A single tomato can produce well over 30 kg of tomatoes. Some other fruiting varieties that perform well are: eggplant (aubergine), capsicum (bell pepper), bean, peas and many more.
What about root crops? No problem, although you are probably better off growing potatoes in the ground, they will still grow successfully in an aquaponic’s grow bed. Carrots are another great root crop in media beds. Carrots harvested from grow beds have no sand on them and although you might wonder how they grow in a bed filled with gravel; they do a surprisingly good job.
Beetroot are another winner. They grow to a fantastic size if you let them go for long enough.
What about deficiencies?
Just as with all gardening, you may get some deficiencies in your plants but generally this can be dealt with very simply. Seaweed extracts are a great way to supplement almost all minerals that might be lacking in an aquaponic system. Seaweed extracts come in many different forms. Consideration towards harmful additives needs to be paramount as anything you add in the system will be passed on to both fish, bacteria, plants and you. You can also use powdered mineral substances. There are a number of different ones on the market, but once again, you must take care in their application if you haven’t used them before. Remember, it’s not just the plants you are caring for but also the fish and the bacteria population. The best way to stay on top of deficiencies is to use a good quality aquaculture feed for your fish. Most good quality feeds have a percentage of ocean caught bi-product and this means that there’s a good range of minerals and trace elements within the fish feed.
Can I plant seeds?
Definitely. Media filled beds generally use a combination of seedlings and seeds. When first planting a grow bed in a new system, sprinkle a mixture of seeds over the grow bed, as well as planting seedlings in the bed. Planting seedlings is simple. We recommend that you use normal seedlings. However, before you plant the seedlings; wash off the majority of the potting mix from the root ball in a small bucket of water. The potting mix should wash off fairly easily with just a gentle shake in the water.
While planting out the seedlings in the beds, the media agitation causes the seeds that were sprinkled over the bed before, to fall down in between the media where it can absorb water and safely germinate. During planting trials this has been found that this method has many benefits. As the seedlings grow and shelter the germinating seeds, they tend to dominate the beds. Many of the germinating seeds can only grow very slowly, however, once the planted seedling matures and gets harvested, this opens up the canopy giving the small plants that germinated from seed a chance to take off. These plants now have a mature root system and a great head start so they can grow very quickly. This mimics natural forest ecosystems, where young trees and other undergrowth grow quite slowly, until a large tree dies and the canopy opens up allowing light to get to the lower plants, which then stimulates their growth.
What are growth rates like?
Growth rates of plants in aquaponic systems can be quite phenomenal. Aquaponic growth rates can exceed hydroponic plant growth by up to four times with some vegetables and herbs. The advantage of aquaponics over soil grown vegetables is that during warm weather the plants get as much water as they need due to the regular flooding of grow beds in an aquaponic system. Plants grown in the ground can use the water around their root system very quickly in hot weather leading to wilting from a lack of water very quickly on a hot day. Plants in an aquaponic system get watered constantly, so they always have water; no matter how hot the weather is.
Can you use compost or soil in a Aquaponic system?
Yes, fill the growing pots with a mixture of coir and compost. The coir is made from discarded coconut husks and helps wick water to the plant’s root system. The compost provides extra nutrient to grow an abundance of crops within the system. Traditional hydroponic growing, or growing without soil, relies on fish waste alone to fertilize the crops. The problem is you can only grow crops with lower nutritional needs such as basil. For example, in most traditional hydroponic systems, Boron is found in very low quantities. Boron is essential for flower development in crops – tomatoes, peppers, and cucumbers – which means that production for these kinds of crops is very low in hydroponic systems. If you are using soil or compost in your system, remember that the dirt will get into your grow tank, use a sump or filter system to help prevent this and say time cleaning your system.
This is a list of plants that grew well for members of online discussion forums. This list is is by no means an exhaustive list of all plants that will grow well. It is just a few of the great performers that forum members have grown.
|Chives||Chillies||Celery||Snow peas||Egg plant|
Of course the plants you grow in your system may be limited by the type of aquaponics system you have or more to the point…the type of plant growing system. If designing your own aquaponic system, you must put some thought into your plant growing method and what you want to grow. This is one of the reasons why we like deep media filled beds at MyOwn Aquaponics. When you have deep media beds, there are no limitations on growing different plants.